Define Delaunay triangulation for n = 0, n = 1 and n = 2. about d3-delaunay

[BTOdell]

Hello Mike,

The n=0 and n=1 cases are easy to work around (it's just the entire bounding area). But the n=2 requires cooperation from the underlying voronoi region algorithm. I'm not super familiar with the mathematics behind delaunay triangulation or voronoi regions or else I'd write up a pull request.

If you could find some time to fix this issue, it would be much appreciated.
Thanks!

[Fil]

Here's my tentative
https://observablehq.com/d/5e4da35146afd543

It's gross (try/catch, and add external points at near-infinity if the triangulation failed). But hey!

[Fil]

Fixed by 2ee9847